The present invention relates to a diffraction grating of a reflective type for diffracting light and an optical multiplexer/demultiplexer using it.
A concave diffraction grating of a reflective type is needed for diffracting light in accordance with its wavelength. A flexible flat-type diffraction grating can be made into a concave diffraction grating by bending it. As such a flexible concave diffraction grating, moreover, is conventionally mounted on a flexible glass substrate. However, such a flexible glass substrate for the flexible replica grating cannot provide sufficient flexibility. That is, a glass substrate of about 0.1 mm thick, before a replica grating is mounted thereon, can only resist bending about a radius of approximately 30 mm. With the replica grating there on, a glass substrate can only resist bending until it finally breaks. As a result the glass substrate has been made thinner to offer more flexibility. However, this causes some trouble in the manufacturing process and is not productive.
Accordingly, an optical multiplexer/demultiplexer comprising a flexible replica grating, a waveguide and a fiber array is now proposed.
Heretofore, high reliable and reasonable optical multiplexer/demultiplexer has not been presented.